Abstracts

Rationale: [11C]-flumazenil-PET (FMZ-PET) has proven to have high sensitivity for localisation of the epileptogenic zone (EZ) in patients with medically refractory focal epilepsy, with a more restricted region of abnormality that FDG-PET. However, practical aspects of [11C] and requirement for arterial blood sampling have limited its clinical application. We have developed a method utilising a new radioliogand, [18F]-FMZ, that does not require arterial blood sampling. In the current study we have assessed [18F]-FMZ-PET for localisation of the EZ in patients with medically refractory focal epilepsy. Methods: Four subject groups were studied; healthy controls (n=20), patients with well-localised temporal lobe epilepsy (TLE) with hippocampal sclerosis on MRI (n=12), patients with well-localised TLE and normal MRI (n=14), and patients with other focal epilepsies (n=4). A 60min dynamic [18F]-FMZ-PET scan and an FDG-PET scan were acquired. Blinded visual assessment of static images was undertaken. Parametric images of binding potential (BP) were generated and region of interest analysis and statistical parametric mapping (SPM) used to localise the EZ. Results: Visual assessment of static images has shown [18F]-FMZ-PET to have high specificity (94%), sensitivity (60.9%) and positive predictive value (87.5%) for the EZ, with a more restricted EZ compared to FDG-PET. Initial SPM results also depict a more restricted area of abnormality on FMZ BP images than FDG; regional analysis is ongoing. Conclusions: Preliminary analyses show that [18F]-FMZ may have improved localisation of the EZ compared with FDG, indicating its potential as a new clinical tool for the evaluation of patients for epilepsy surgery.